The present invention relates to producing alkoxysilanes and alkoxy-oximinosilanes which are useful as initiators or room temperature vulcanizing agents in silicone rubber compounds.
Prior art processes for the production of alkoxysilanes have involved the reaction of silicon chlorides such as methyltrichlorosilane (MTCS) with alcohols, with strong bases such as pyridine or sodium metal used to neutralize the byproduct HCl and drive the reaction to completion. Similar processes have been disclosed for producing oximinosilanes, with an oxime substituted for the alcohol.
In Russian Author's Certificate No. 547,245 of G. V. Ryasin et al., (published May 22, 1981), a process is described in which an oxime acts as both reactant and acid acceptor, such that six moles of methyl ethyl ketoxime (MEKO) and one mole of MTCS produce one mole of methyl tris(methyl ethyl ketoximo) silane and three moles of MEKO hydrochloride. Our copending, commonly assigned U.S. application Ser. No. 331,694 (filed Dec. 17, 1981) discloses such a process in which the product is recovered without requiring a product distillation.
Oximinosilanes are superior in performance to alkoxysilanes as initiators for silicone rubbers because of more rapid hydrolysis. Alkoxysilanes have the advantage of cheaper raw materials cost. The advantages of both materials might be obtained by using some of each in a molding composition. A more desirable alternative would be to combine both functionalities on the same molecule. See German Offen No. 2,055,712 (1971) (Chem Abstr 75:89238c); 2,065,407 (1973) (Chem Abstr 80:4671u); and Japan No. 74:39,967 (1974) (Chem Abstr 83:179292k).